VK_FORMAT_R8G8B8_* and VK_FORMAT_B8G8R8_* are 24-bit formats. DRM_FORMAT_XBGR8888 and DRM_FORMAT_XRGB8888 aren't suitable to implement these, since they are 32-bit.
Instead, use DRM_FORMAT_BGR888 and DRM_FORMAT_RGB888, which have the correct depth.
Ref !14588 (merged) for the previous format fixes (which didn't touch 24-bit RGB formats).
cc @DadSchoorse